Light source unit having a microlens array for converting excitation light into plural light ray bundles and projector including the light source unit

ABSTRACT

To provide a projector which enables a stable projection for a long period of time, there is provided a projector comprising a light source unit, a display device, a projection-side optical system, a light guiding optical system and a projector control unit, wherein the light source unit comprises an excitation light source unit comprising an excitation light source and a microlens array and a rectangular green luminescent plate which receives light emitted from the excitation light source to emit light in a green wavelength band, and the microlens array is disposed between the excitation light source and the luminescent plate and has a plurality of micro convex lenses which each have a similar shape to the shape of the luminescent material layer are arranged into a matrix, so as to convert light from excitation light source into a plurality of pencils of light to shine them onto the luminescent plate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of U.S. Ser. No. 13/070,785filed on Mar. 24, 2011, which is based upon and claims the benefit ofpriority under 35 USC 119 of Japanese Patent Application No. 2010-067134filed on Mar. 24, 2010, the entire disclosure of which, including thedescription, claims, drawings and abstract thereof, is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light source unit having aluminescent plate which becomes luminous based on energy from anexcitation light source and a projector which includes the light sourceunit.

2. Description of the Related Art

In these days, data projectors are used on many occasions as imageprojection apparatuses which project images including images of screensand video images of personal computers, as well as images based on imagedata which is stored in memory cards on to a screen. In projectors ofthe type described above, conventionally, projectors using ahigh-intensity discharge lamp as a light source have been the mainstreamof projectors. However, in recent years, there have been made manydevelopments and proposals on projectors which use, as a light source,alight emitting diode (LED), a laser emitter, a device utilizing organicEL technology or luminescent materials.

For example, Japanese Unexamined Patent Publication No. 2004-341105(JP-A-2004-341105) proposes a light source unit in which red, green andblue luminescent material layers are laid end to end on a surface of aluminescent plate made up of a light transmissive circular plate and adichroic filter which transmits ultraviolet light and reflects visiblelight is disposed on a back side of the luminescent plate and whichgenerates a light-source light of red wavelength band, a light-sourcelight of green wavelength band and a light-source light of bluewavelength band by shining ultraviolet light onto the luminescentmaterial layers from the back side of the luminescent plate.

As has been described above, there exist projectors which utilize, as alight-source light, luminescent light emitted from a luminescentmaterial of a luminescent material layer by shining light emitted froman excitation light source to the luminescent material layer. In theseprojectors, the quantity of luminescent light emitted from theluminescent material of the luminescent material layer can be increasedby increasing the output of the excitation light source. However, when alaser emitter is used as an excitation light source, in the event thatthe power of a laser beam emitted from the laser emitter is increased,there has been caused a fear that the luminance saturation of theluminescent material or a failure thereof attributed to scorching isgenerated.

On the other hand, when a laser beam is shone onto the luminescentmaterial layer while being diffused to weaken the power per unit area ofthe laser beam with the power of the laser bean being increased, thearea illuminated by the laser beam gets wider than the area of theportion of the luminescent material layer that is to be illuminated bythe laser beam, whereby the laser beam is shone onto positions which lieout of the luminescent material layer, leading to a problem that theutilization efficiency of light emitted from the laser emitter isdecreased.

SUMMARY OF THE INVENTION

The invention has been made in view of the problem inherent in therelated art and an object thereof is to provide a light source unitwhich can prevent the luminance saturation of a luminescent material ora failure thereof which is attributed to scorching and increase theutilization efficiency of excitation light so that the luminescentmaterial becomes luminous uniformly, and a projector which includes thislight source unit to thereby enable a projection which is free fromluminance non-uniformity and remains stable for a long period of time.

According to an aspect of the invention, there is provided a lightsource unit comprising an excitation light source unit, a luminescentplate including a luminescent material layer which becomes luminous byutilizing light emitted from the excitation light source as excitinglight, a microlens array which is interposed between the excitationlight source and the luminescent plate and which converts light emittedfrom the excitation light source into a plurality of pencils of light soas to shine the plurality of pencils of light onto the luminescentplate, and a collective lens which is disposed in proximity to theluminescent plate and which shines the plurality of pencils of lightonto the luminescent plate so that center positions of the plurality ofpencils of light are superposed one on another on the luminescentmaterial layer.

According to another aspect of the invention, there is provided aprojector comprising the light source unit.

According to the aspects of the invention, there can be provided thelight source unit which can prevent the luminance saturation of theluminescent material or the failure thereof which is attributed toscorching and increase the utilization efficiency of excitation light sothat the luminescent material becomes luminous uniformly, and theprojector comprising this light source unit to thereby enable aprojection which is free from luminance non-uniformity and remainsstable for a long period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be understood much sufficiently by reading thefollowing detailed description thereof and referring to the accompanyingdrawings. However, the detailed description and the accompanyingdrawings are intended mainly to describe the invention and are notintended to limit the scope thereof. In the accompanying drawings;

FIG. 1 is a perspective view showing an external appearance of aprojector according to an embodiment of the invention,

FIG. 2 is a functional circuit block diagram showing functional blocksof the projector according to the embodiment of the invention,

FIG. 3 is an exemplary plan view showing an internal construction of theprojector according to the embodiment of the invention with an uppercase removed,

FIG. 4A is a front view of a microlens array according to the embodimentof the invention,

FIG. 4B is a sectional view of the microlens array according to theembodiment of the invention,

FIG. 5 is an explanatory drawing regarding flows of pencils of light inan exciting light shining unit and a luminescent plate according to theembodiment of the invention, and

FIG. 6 is an explanatory drawing showing an exciting light luminancedistribution of the luminescent plate according to the embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, a preferred mode for carrying out the invention will bedescribed by use of the accompanying drawings. Although variouslimitations which are technically preferable in carrying out theinvention are imposed on an embodiment which will be described below,the scope of the invention is not limited in any way to the followingdescription and illustrated examples.

A projector 1 according to the invention includes a light source unit60, a display device 51, a projection-side optical system, a lightguiding optical system 170 for guiding light from the light source unit60 to the display device 51 and for aligning a optical axis of aprojection light which is generated in the display device 51 with aoptical axis of the projection-side optical system, and a projectorcontrol unit for controlling the light source unit 60 and the displaydevice 51.

The light source unit 60 includes an excitation light shining device 70which includes in turn an excitation light source 71 and a microlensarray 75, a luminescent plate 101 which includes a green luminescentmaterial layer which receives light emitted from the excitation lightsource 71 to emit light in a green wavelength band, a red light source121 which emits light in a red wavelength band, a blue light source 301which emits light in a blue wavelength band, and a light source-sideoptical system 140 which alters optical axes of the light in the redwavelength band, the light in the green wavelength band and the light inthe blue wavelength band to the same optical axis and guides the red,green and blue light to a predetermined plane.

The microlens array 75 is interposed between the excitation light source71 and the luminescent plate 101 and converts light emitted from theexcitation light source 71 into a plurality of pencils of light so as toshine them onto the luminescent plate 101. A front surface of theluminescent plate 101 is formed into a reflecting plane, and arectangular luminescent material layer is laid on the reflecting plane.In addition, the microlens array 75 has a plurality of micro convexlenses 75 a having a similar shape to that of the luminescent materiallayer and arranged in a matrix.

In the light source unit 60, a collective lens 110 is disposed inproximity to the luminescent plate 101, and pencils of light that havepassed through the micro convex lenses 75 a are shone onto theluminescent material layer by the collective lens 110 so that centerpositions thereof are superposed one on another on the luminescentmaterial layer.

Hereinafter, an embodiment of the invention will be described in detailby reference to the accompanying drawings.

FIG. 1 is a perspective view showing an external appearance of aprojector 1. In this embodiment, left and right with respect to theprojector 1 denote, respectively, left and right directions with respectto a projecting direction, and front and rear denote, respectively,front and rear directions with respect to the projecting direction ofthe projector 1 and a traveling direction of pencils of light.

As is shown in FIG. 1, the projector 1 is a small, substantiallyrectangular parallelepiped projector 1 which can rest in the hand, andits interior is covered by an upper case and a lower case 6. A lensbarrel 225 is disposed substantially in a center of a front panel 12which is made by fitting together portions of the upper case 5 and thelower case 6 which are situated at a front of a projector casing, andoutside air inlet openings 18 are formed in the front panel 12 which isproximity of a right-hand side panel 15.

In addition, a keys/indicators part 37 is provided on an upper panel 11which is formed by the upper case 5 of the projector housing. Disposedon this keys/indicators part 37 are keys and indicators which include apower supply switch key, a power indicator which informs whether thepower supply is on or off, a projection switch key which switches on oroff projection, an overheat indicator which informs that the lightsource unit, the display device or a control circuit overheats. Further,provided in a back panel 13 and the right-hand side panel 15 which areformed by fitting together portions of the upper case 5 and the lowercase 6 which are situated at the rear and side of the projector housingare various types of terminals such as USB terminals, a power supplyadapter plug, memory card insertion slots and the like.

Next, a projector control unit of the projector 1 will be described byuse of a functional block diagram in FIG. 2. The projector control unitincludes a control unit 38, an input/output interface 22, an imagetransforming unit 23, a display encoder 24, a display drive unit 26 andthe like. The control unit 38 governs the control of operations ofrespective circuitries within the projector 1, and the control unit 38is made up of a CPU as an arithmetic unit, a ROM which stores operationprograms such as various types of settings in a fixed fashion and a RAMwhich is used as a work memory.

The projector control unit sends image signals of various standards thatare inputted from an input/output connector unit 21 to the imagetransforming unit 23 via the input/output interface 22 and a system bus(SB) where the image signals are transformed into image signals in apredetermined unified format which is suitable for display andthereafter, the image signals so transformed are outputted to thedisplay encoder 24.

In addition, the display encoder 24 deploys the image signals inputtedthereinto on a video RAM 25 for storage and generates a video signalfrom the contents stored in the video RAM 25, outputting the videosignal so generated to the display drive unit 26.

The display drive unit 26 functions as a display device controller anddrives a display device 51 which is a spatial optical modulator (SOM) atan appropriate frame rate in accordance with image signals outputtedfrom the display encoder 24. In this projector 1, pencils of light whichare emitted from a light source unit 60, that is, pencils of light whichare collected to a predetermined plane by a light source-side opticalsystem 140 of the light source unit 60 are shone onto the display device51 via a light guiding optical system 170 to thereby form an opticalimage by reflected light reflected at the display device 51 which iscontrolled to be driven by the display drive unit 26. The image soformed is projected on to a screen, not shown, for display via aprojection-side optical system, which will be described later. A movablelens group 235 of the projection-side optical system is driven by a lensmotor 45 for zooming or focusing.

In addition, an image compression/expansion unit 31 performs anoperation in which when in a reproducing mode, the imagecompression/expansion unit 31 reads out image data recorded on a memorycard 32 and expands individual image data which make up a series ofdynamic images frame by frame. Then, the image data is outputted to thedisplay encoder 24 via the image transforming unit 23 so as to enablethe display of dynamic images on the basis of the image data stored onthe memory card 32.

Operation signals generated at the keys/indicators part 37 which isprovided on the upper case 5 are sent out directly to the control unit38. A voice processing unit 47 is connected to the control unit 38 via asystem bus (SB). This voice processing part 47 includes a sound sourcecircuit such as a PCM sound source. When in a projection mode and areproducing mode, the voice processing unit 47 converts voice data intoanalog signals and drives a speaker 48 to output loudly sound or voicebased on the voice data.

Additionally, the control unit 38 controls a light source controlcircuit 41 which is configured as alight source control unit. This lightsource control circuit 41 controls individually the emission of light byan excitation light shining unit, a red light source unit and a bluelight source unit of the light source unit 60 so that a light sourcelight in a predetermined wavelength band which is required whengenerating a image is emitted from the light source unit. Further, thecontrol unit 38 causes a cooling fan drive control circuit 43 to detecttemperatures through a plurality of temperature sensors which areprovided in the light source unit 60 so as to control rotating speeds ofa cooling fan based on the results of the temperature detection.

Further, the projector control unit includes an illuminance sensor 42 asan illuminance measuring unit for measuring an illuminance of lightemitted from the light source unit 60. Then, the control unit 38regulates voltages applied to the respective light sources of the lightsource unit 60 based on information regarding outputs of light inrespective wavelength bands which are sent out from the illuminancesensor 42 and maintains an original luminance balance when the projector1 is shipped from a factory.

Next, an internal construction of the projector 1 will be described.FIG. 3 is an exemplary plan view showing an internal construction of theprojector 1. As is shown in FIG. 3, the projector 1 includes the lightsource unit 60 at a central portion, the lens barrel 225 whichincorporates a projection-side optical system to the left of the lightsource unit 60 and a battery 55 which lies between the lens barrel 225and a left-hand side panel 14. In addition, the projector 1 includes thedisplay device 51 such as a DMD disposed parallel to the left-hand sidepanel 14 in a position lying in proximity to the battery 55 between thelens barrel 225 and the back panel 13. Further, the projector 1 includesa main control circuit board 241 below the light source unit 60 and apower supply control circuit board 242 between the lens barrel 225 andthe battery 55.

In addition, the projector 1 includes light source unit and the lightguiding optical system 170 between the lens barrel 225 and the backpanel 13. The light guiding optical system 170 shines light emitted fromthe light source unit 60 onto the display device 51 and makes an opticalaxis of light reflected at the display device 51 coincide with anoptical axis of the projection-side optical system for emission towardsthe projection-side optical system. The projector 1 further includes apower supply connector 80, a heatsink 190 for a red light source 121,which will be described later, a heat pipe 130 for guiding heatgenerated in an excitation light source 71 and a blue light source 301,both of which will be described later, to the heatsink 190, and acooling fan 261 sequentially in that order from the back panel 13between the light source unit 60 and the right-hand side panel 15.

The light source unit 60 includes an excitation light shining unit 70which is disposed in proximity to the cooling fan 261 and the frontpanel 12, a blue light source unit 300 which is disposed between theexcitation light shining unit 70 and the lens barrel 225, a luminescentplate 101 which is disposed in proximity to the light source connector80 and the back panel 13, a red light source unit 120 which is disposedbetween the excitation light shining unit 170 and the luminescent plate101, and a light source-side optical system 140 which guides light inred, green and blue wavelength bands emitted from the light source unit60 to the light guiding optical system 170.

The excitation light shining unit 70 includes two excitation lightsources 71 whose optical axes are parallel to the left-hand side panel14, two collimator lenses 73 which are disposed on the optical axes ofthe excitation light sources 72 and a microlens array 75 which isdisposed in front of the collimator lenses 73. This excitation lightsource 71 is a blue laser emitter and emits a laser beam in a bluewavelength band towards the luminescent plate 101. In addition, theexcitation light source 71 is in contact with the heat pipe 130 via acircuit board for the excitation light source 71 and is cooled by theheatsink 190 via this heat pipe 130. The collimator lenses 73 convertlight emitted from the excitation light source 71 into parallel pencilsof light to be shone onto the microlens array 75. The microlens array 75will be described in detail later.

The luminescent plate 101 has a rectangular shape and a surface of theluminescent plate 101 is mirror finished. A rectangular greenluminescent material layer is laid on the mirror finished surface. Thisgreen luminescent material layer is formed of a binder of a siliconeresin having high heat resistance and transmissivity and a greenluminescent material which is dispersed uniformly in the binder. Then,the luminescent plate 101 generates green luminescent light by use of alaser bean emitted from the excitation light source 71 as excitationlight and emits this green luminescent light from the same plane as theincident plane of the excitation light. The green luminescent materiallayer of the luminescent plate 101 has a similar shape to that of thedisplay device 151, and a sectional shape of a pencil of light emittedfrom the green luminescent material layer approximates to the shape ofthe display device 51.

The red light source unit 120 includes the red light source 121 whichoptical axis is parallel to the front panel 12. This red light source121 is a red light emitting diode and is cooled by the heatsink 190. Theblue light source unit 300 includes the blue light source 301 whoseoptical axis is parallel to the excitation light source 71. This bluelight source 301 is a blue light emitting diode and is cooled by theheat sink 190 via the heat pipe 130.

The light source-side optical system 140 includes a collective lens 110which collects light emitted from the excitation shining unit 70 andluminescent light emitted from the luminescent plate 101, a collectivelens 125 which collects light emitted from the red light source 121, acollective lens 305 which collects light emitted from the blue lightsource 301, a first dichroic mirror 141 which transmits excitation lightfrom the excitation light shining unit 70 and light from the red lightsource unit 120 and reflects luminescent light emitted from theluminescent plate 101, and a second dichroic mirror 142 which reflectslight from the red light source unit 120 and luminescent light emittedfrom the luminescent plate 101 and transmits light emitted from the bluelight source unit 300.

The collective lenses 110, 125, 305 are each configured as a singlecollective lens by combining a plurality of lenses. In addition, thefirst dichroic mirror 141 is disposed in a position where the opticalaxis of the excitation light shining unit 70 and the optical axis of thered light source unit 120 intersect each other. Further, the seconddichroic mirror 142 is disposed in a position where the optical axis ofthe red light source unit 120 and the optical axis of the blue lightsource unit 300 intersect each other.

In a light source unit in which a luminescent material is caused to beluminous by use of light emitted from a laser emitter as excitationlight, pencils of light emitted from the excitation light source, whichis a laser emitter, have a high directivity and a very strong peakpower, and therefore, there has been caused a fear that such pencils oflight are shone strongly onto part of the luminescent material layer tothereby cause a luminance saturation or a failure due to scorching.Then, in the light source unit 60 of this embodiment, by disposing themicrolens array 75 in front of the excitation light source 71 in the waydescribed above, the laser beam having the strong peak power isconverted into pencils of light each having the similar sectional shapeto the luminescent material layer which are then shone onto the whole ofthe luminescent plate 101 substantially uniformly.

FIG. 4 shows an exemplary front view and an exemplary sectional view ofthe microlens array 75. As is shown in FIGS. 4A and 4B, in the microlensarray 75 of the excitation light shining unit 70, a plurality of microconvex lenses 75 a are arranged into a matrix. In addition, each microconvex lens 75 a has a substantially similar shape to the shape of thegreen luminescent material layer of the luminescent plate 101. Pencilsof light which are incident on the microlens array 75 are converted intoa plurality of pencils of light by the micro convex lenses 75 a, and apencil of light incident on each micro convex lens 75 a is convertedinto a pencil of light having a rectangular section by the micro convexlens 75 a.

In addition, as is shown in FIG. 5, the excitation light is convertedinto a plurality of pencils of light having the rectangular section bythe microlens array 75, and the pencils of light are then collected bythe collective lens 110 so as to be shone onto the green luminescentmaterial layer of the luminescent plate 101. Namely, the pencils oflight that have passed through the micro convex lenses 75 a arecollected by the collective lens 110 so that their center positions aresuperposed one on another on the green luminescent material layer,whereby the plurality of pencils of light having the rectangular sectionare shone onto the whole of the green luminescent material layer one onanother. In addition, FIG. 6 shows a distribution 103 of excitationlight shone via the microlens array 75. Since each pencil of light isgiven the substantially similar section to the shape of the greenluminescent material layer 102, the excitation light is shone onto awide range on the green luminescent material layer 102 with a uniformintensity. Consequently, the pencils of light like the laser beam havingthe strong peak power can be shone onto the wide range of the greenluminescent material layer 102 with the uniform intensity, andtherefore, the generation of a luminance saturation or a failure due toscorching of the luminance material can be prevented, thereby making itpossible to allow the luminescent material to become luminous uniformly.

In the light source unit 60 of the embodiment, although the singlemicrolens array 75 is disposed in front of the two excitation lightsources 71, the invention is not limited thereto. For example, amicrolens array 75 may be disposed in front of each microlens array 75.Alternatively, the light source unit 6 may be made up of a singleexcitation light source 71 having a high luminance and a singlemicrolens array 75.

The light guiding optical system 170 includes a microlens array 171, anoptical axis alteration mirror 173 for altering an axis of light emittedfrom the light source unit 60 towards the display device 51, acollective lens 172 which is interposed between the optical axisalteration mirror 173 and the microlens array 171, a collective lens 174which is positioned on the optical axis which is altered by the opticalaxis alteration mirror 173 and a prism 175.

The microlens array 171 in this light guiding optical system 170converts the pencils of light which are emitted from the red lightsource 121, the blue light source 301 and the luminescent plate 101 inthe light source unit 60 into a plurality of pencils of light having arectangular section which matches the shape of the display device 51,and the pencils of light are then collected by the microlens array 171or the collective lens so that center positions of the pencils of lightare superposed one on another on the display device 51 whereby thepencils of light are mixed so that the pencils of light are convertedinto a pencil of light having a uniform intensity distribution. Namely,the microlens array 171 functions as a light guiding unit such as alight tunnel or a glass rod which converts pencils of light which areincident thereon into a pencil of light having a rectangular section anda uniform intensity distribution. The prism 175 functions as a condenserlens which shines light-source light onto the display device 51 and anoptical axis alteration unit which alters an optical axis of projectionlight generated in the display device 51 so as to coincide with anoptical axis of the projection-side optical system incorporated in thelens barrel 225.

The projection-side optical system incorporated in the lens barrel 225includes a fixed lens group and a movable lens group and realizes azooming function and a focusing function by causing lenses of themovable lens group to operate in an optical direction by controlling thelens motor 45.

In addition, the battery 55 is a drive power supply for the projector 1and constitutes a secondary battery which can be charged by beingconnected to a commercial power supply. A secondary battery such as alithium-ion battery or a nickel-hydrogen battery can be applied to thebattery 55. Then, images can be projected by the projector 1 of theembodiment by the electric power of the battery 55 without beingconnected to a power supply via an electric cord.

In this way, in the projector 1 of the embodiment, the excitation lighthaving the uniform intensity can be shone onto the wide range on theluminescent material layer of the luminescent plate 101 by disposing themicrolens array 75 in front of the excitation light source 71.Consequently, the generation of a luminance saturation or a failure dueto scorching of the luminescent material can be prevented, which enablesthe luminescent material to become luminous more uniformly, therebymaking it possible to provide the projector 1 which enables the stableprojection free from luminance non-uniformity for a long period of time.

In addition, the pencils of light having the circular section which areemitted from the excitation light source 71 can be converted into theplurality of pencils of light having the rectangular section by formingthe microlens array 75 by arranging the plurality of micro convex lenses75 a into the matrix which each have the similar shape to the shape ofthe luminescent material layer. Consequently, compared with a situationin which pencils of light having a circular section are shone onto aluminescent material layer having a rectangular shape, the excitationlight can be shone onto the wide range on the luminescent materiallayer, thereby making it possible to increase the utilization efficiencyof the luminescent material. In this embodiment, while the luminescentmaterial layer 102 and the micro convex lenses 75 a have the rectangularshapes, their shapes are not limited to the rectangular shapes, providedthat the shapes of the luminescent material layer and the micro convexlenses are similar to each other as has been described above. Forexample, the luminescent material layer 102 and the micro convex lenses75 a may have circular shapes or polygonal shapes. Namely, any shapescan be adopted, provided that light emitted from the excitation lightsource 71 may be converted into pencils of light having the same shapeas that of the luminescent material layer.

By collecting the plurality of pencils of light generated in themicrolens array 75 so that their center positions are superposed one onanother on the luminescent material layer by the collective lens 110,the plurality of pencils of light each having a weak power can be shoneonto the luminescent material layer in a superposed fashion. Therefore,light having a strong power can be prevented from being shone onto onlya specific area of the luminescent material layer, whereby thegeneration of a luminance saturation of or a failure due to scorching ofthe luminescent material can be prevented, thereby making it possible tomake the luminescent material become luminous further uniformly.

In addition, since the light source unit 60 of the embodiment includesthe red light source 121 and the blue light source 301 in addition tothe excitation light source 71 and the luminescent plate 101, the lightsource unit 60 can generate the light in the red wavelength band, thelight in the green wavelength band and the light in the blue wavelengthband, which constitute the three primary colors of light, whereby thelight source unit 60 can be used as alight source unit in the projector1 which can project color images.

In the projector 1 of the embodiment, while only the light in the greenwavelength band is made to be generated by the luminescent plate 101,the invention is not limited thereto. A configuration may be adopted inwhich the light in the red wavelength band or the light in the bluewavelength band is generated by making use of luminescent plates. Asthis occurs, too, as in the case with this embodiment, by disposing themicrolens array 75 in front of the excitation light source 71, thegeneration of a luminance saturation of or a failure due to scorching ofthe luminescent material can be prevented, and the utilization of theluminescent material can be increased, thereby making it possible tomake the luminescent material become luminous further uniformly.

In addition, since the luminescent material does not have to be rotatedin order to prevent the generation of a luminance saturation of or afailure due to scorching of the luminescent material, it becomespossible to obviate the necessity of a motor for rotationally drivingthe luminescent material in order to prevent the generation of aluminance saturation of or a failure due to scorching of the luminancematerial, whereby the light source unit 60 and the projector 1 can bemade smaller in size.

In addition, the invention is not limited to the embodiment that hasbeen described heretofore and can be modified variously in steps ofcarrying out the invention without departing from the spirit and scopeof the invention. Additionally, the invention may be carried out with asmany functions as possible in the functions which are described as beingexecuted in the embodiment described above combined together asrequired. The embodiment includes various steps, and various inventionscan be extracted by combining the plurality of disclosed constituentrequirements as required. For example, in the event that an advantagecan be obtained even though some constituent requirements are deletedfrom the whole constituent requirements, the resulting configuration inwhich some of the constituent requirements are so deleted can beextracted as the invention.

What is claimed is:
 1. A light source unit comprising: an excitationlight source; a blue light source which emits light in a blue wavelengthband; a luminescent plate comprising a luminescent material layer whichemits luminescent light by receiving light emitted from the excitationlight source; a microlens array which is disposed between the excitationlight source and the luminescent plate and which converts light emittedfrom the excitation light source into a plurality of pencils of light soas to be shone onto the luminescent plate; and a collective lens whichis disposed in proximity to the luminescent plate and which shines theplurality of pencils of light so that their center positions aresuperposed one on another on the luminescent material layer; a dichroicmirror which makes an optical axis of the blue light source and anoptical axis of the luminescent light coincide with each other on thesame optical axis.
 2. A light source unit as set forth in claim 1,wherein a surface of the luminescent plate is formed into a reflectingplane and the luminescent material layer having a predetermined shape islaid on the luminescent material layer, and wherein the microlens arrayis made up of a plurality of micro convex lenses which each have asimilar shape to the shape of the luminescent material layer and whichare arranged into a matrix.
 3. A light source unit as set forth in claim1, wherein the luminescent material layer has a rectangular shape.
 4. Alight source unit as set forth in claim 2, wherein the luminescentmaterial layer has a rectangular shape.
 5. A light source unit as setforth in claim 1, comprising: an excitation light shining unitcomprising the excitation light source and the microlens array; theluminescent plate comprising a green luminescent material layer whichreceives light emitted from excitation light source so as to emit lightin a green wavelength band; a red light source which emits light in ared wavelength band; a blue light source which emits light in a bluewavelength band; and a light source-side optical system which altersoptical axes of the light in the red wavelength band, the light in thegreen wavelength band and the light in the blue wavelength band into thesame optical axis so as to guide the light in the red, green and bluewavelength bands to a predetermined plane.
 6. A light source unit as setforth in claim 2, comprising: an excitation light shining unitcomprising the excitation light source and the microlens array; theluminescent plate comprising a green luminescent material layer whichreceives light emitted from excitation light source so as to emit lightin a green wavelength band; a red light source which emits light in ared wavelength band; a blue light source which emits light in a bluewavelength band; and a light source-side optical system which altersoptical axes of the light in the red wavelength band, the light in thegreen wavelength band and the light in the blue wavelength band into thesame optical axis so as to guide the light in the red, green and bluewavelength bands to a predetermined plane.
 7. A light source unit as setforth in claim 3, comprising: an excitation light shining unitcomprising the excitation light source and the microlens array; theluminescent plate comprising a green luminescent material layer whichreceives light emitted from excitation light source so as to emit lightin a green wavelength band; a red light source which emits light in ared wavelength band; a blue light source which emits light in a bluewavelength band; and a light source-side optical system which altersoptical axes of the light in the red wavelength band, the light in thegreen wavelength band and the light in the blue wavelength band into thesame optical axis so as to guide the light in the red, green and bluewavelength bands to a predetermined plane.
 8. A light source unit as setforth in claim 4, comprising: an excitation light shining unitcomprising the excitation light source and the microlens array; theluminescent plate comprising a green luminescent material layer whichreceives light emitted from excitation light source so as to emit lightin a green wavelength band; a red light source which emits light in ared wavelength band; a blue light source which emits light in a bluewavelength band; and a light source-side optical system which altersoptical axes of the light in the red wavelength band, the light in thegreen wavelength band and the light in the blue wavelength band into thesame optical axis so as to guide the light in the red, green and bluewavelength bands to a predetermined plane.
 9. A projector comprising:the light source unit set forth in claim 1; a display device; aprojection-side optical system; a light guiding optical system whichguides light emitted from the light source unit to the display deviceand make the projection light generated in the display device coincidewith an optical axis of the projection-side optical system; and aprojector control unit for controlling the light source unit and thedisplay device.